version key should be in the second possition in the Bandwidth File
According to the spec: https://gitweb.torproject.org/torspec.git/tree/bandwidth-file-spec.txt?id=698d6301a409c8ebb2db389d06d2ee8f40d0fa3a#n152
But i can create a Bandwidth File with version in other position:
>>> content = """1523911758
... earliest_bandwidth=2019-02-14T16:06:24
... version=1.2
... =====
... bw=760 node_id=$68A483E05A2ABDCA6DA5A3EF8DB5177638A27F80 nick=Test"""
... bwfile = BandwidthFile.from_str(content)
...
...
>>> str(bwfile)
'1523911758\nearliest_bandwidth=2019-02-14T16:06:24\nversion=1.2\n=====\nbw=760 node_id=$68A483E05A2ABDCA6DA5A3EF8DB5177638A27F80 nick=Test'
>>>
When generating the string, the version should be in the second position. When parsing the string, i'm not sure if we should assume that is version 1.0 and ignore all the other headers or because stem is able to parse it, ignore the error and accept it's version 1.2